Removal of various undesirable components from whole blood is well known and often includes ex vivo separation of cellular components (e.g., centrifugation or filtration) to obtain a cell-free fluid that is then processed, typically using affinity media and/or enzymatic treatment. While such treatment is standard practice in many instances, hemolysis is often a problem. Still more disadvantageously, such known treatment typically requires relatively large equipment and is therefore impractical in ambulatory use.
Further known methods for binding of a contaminant from a fluid are described in WO 2011/005742 where a sorbent medium is modified and combined with the fluid. However, the sorbent medium must be separated from cellular components, which is in most cases not feasible to the required degree. To assist in separation of the sorbent, magnetic beads can be used as is described in U.S. Pat. No. 6,143,510. However, such methods are generally limited to ex vivo tests as residual quantities of magnetic beads are highly undesirable. To circumvent problems associated with removal of sorbent, selective permeable membranes may be employed as taught in US 2009/0114595. While such removal is conceptually simple, separation efficiency is in at least some cases less than desirable, especially where large molecules are separated. Thus, there is still a need to provide improved whole blood separation devices and methods.